Optimal Regorafenib Combinations in Pediatric Rhabdomyosarcomas

Dieter Zopf, Principal Scientist at Bayer AG, Research and Development, Pharmaceuticals, Oncology, discusses the optimal partner for regorafenib (Stivarga) in pediatric rhabdomyosarcomas.

In the study analyzing effective combinations with regorafenib for the treatment of pediatric rhabdomyosarcomas, irinotecan (Onivyde) was identified as the best drug to use in combination with regorafenib based on its anti-tumor activity. As these are both potent single agents, researchers had to determine that there was a synergistic benefit with the combination, explains Zopf.

The growth curve following treatment with bone irinotecan alone and irinotecan plus regorafenib showed tumor shrinkage until it was gone. Researchers gave treatment for 4 weeks and then looked at the time to progression. The tumor stayed low or absent for 2 or 3 weeks, notes Zopf. Researchers saw that the tumor regrew in the irinotecan arm as opposed to the combination arm—which saw no regrowth after approximately 80 days. This confirmed that irinotecan is most likely the best combination partner with regorafenib, says Zopf.